I found a couple threads on this topic but wanted to start a nice, consolidated conversation, with a fresh and descriptive title. Thanks to Konigster's service sheet, I was able to identify a few maintenance items that I now want to pursue. Below are the things I plan on tackling in the next couple weeks:
-Camshaft solenoids (4x) and position sensors (4x) along with the sacrificial harnesses (8x)
-Spark plugs and coils (not sure if this was ever done, I don't see it in the maintenance records)
-Transmission fluid flush/replacement (also not sure if this was ever done, I don't see it in the maintenance records)
-Engine filter swap (2x)
-Cabin filter swap (1x)
-Clean and lubricate pano roof

With that, are there any other things that are jumping out to peeps? Like "you gotta do the..." as well? Again, this is all preventative. My car is running great right now and I want to keep it that way!

 

Check the motor mounts/transmission mount. Also assuming you don't have airmatic, check the status of the shocks/strutus and coil springs, they get weak with time and sag a little.

 

I would insect solenoids before replacing them
You have pretty good bet on MM, when transmission mount usually last much longer.
Add clay/wax job. The car deserves it.

 

I'm looking at the solenoids as an insurance policy. I paid under $500 for all the parts and my buddy is doing the install for next to nothing. I don't want to ever worry about the oil wicking issues with these cars...

Making the exterior like new will be my next task after all this stuff. Cars paint is in fantastic condition so it just needs a little love!

 

You GOTTA change the ATF on these fairly often they start to go bad as soon as 20k, factory fills start not having it as early as 40k into a new car. The thinner formula doesn't have the same longevity as the old red stuff. When I do drains at 30-40k now it smells completely burnt, the viscosity is nothing like the new stuff, and the magnets are just full as hell the cars will shudder, idle loud, and not pull very hard especially in the sport mode. After the fluid exchange they feel brand new again. If you think you gotta do it, just do it. The most economical solution is the Febi/Bilstein ATF134 FE stuff. The OEM stuff is produced by Shell/Helinox and isn't commercially available to us here. It's not that exotic, everybody uses a thin ATF these days, even Valvoline says their RED Maxlife universal works with 236.16 lol. Filter kit you should use with the bolts/filter/gasket/plug/washer is the VAICO one. I use Amsoil but I'm not gonna shill it here.

You also don't need a fancy fluid extractor/pump like a Mityvac 7201 or the alternative to do the service it's actually an incredible pain in the *** to do it this way. I've bought 3 and all the seals fail and I HATE them for it, so I just use a $10 Slippery Pete handpump and 722.9 ATF adapter off amazon. You will drain something like 4.5 liters, buy six for insurance or to do a little 1 liter flush later. The 7L fill assumes youre going to drain the TC which is more trouble than it's worth for 99% of people. You can do this for the same difficulty as an oil change honestly and I bill $550 for the service. Buy two sets of bolts in case the gasket rolls so you don't re-use a stretched bolt, Elring or Corteco make the good ones for this application.

For the cabin filter use either the Hengst Biofunctional, or the Mahle Caremetix biofunctional. I loathe the Mann carbon/biofunctional ones because they come with a replacement clip that NEVER fits. Filtration is good but not as good as the others I mentioned too. The Mann or Hengst filters are the best. I use Hengst for the tight seal, plastic top, and white cap o-ring.

As for plugs/coils you can get by honestly just inspecting them and checking their gap and if they're eroding at an angle or something. Most coils won't malfunction without throwing a code or giving you a lumpy idle, but it's not really a service interval thing for me unless the car is like 15 years old. You can inspect and replace the boots and springs on them though they get a lil baked from the heat. The double platinum recommendation of being changed every 60k is a BIT conservative, I keep having to replace new looking plugs for $600+ at the shop and I feel bad. I have a pile of Bosch/NGK double plats for my car for a long time.

I don't want to sound cheap but the solenoids/magnets and pigtail harness is a bit much if you don't notice anything. I completely acknowledge that it's a thing, but but but if your magnets are in good order just inspect your engine with a mirror every now and then. You'll also smell oil.

I'm more of an inspect and diagnose guy, it tends to stave off resentment towards a car for it's upkeep costs if you can spread it out and do things as they're needed instead of some arbitrary service interval. If I did every single control arm at the recommended 100k I would have missed out on like 40k of completely perfect driving for example, and I have a blank check for parts, I just find fixing my own cars instead of customers' cars a huge drag.

As for the sunroof, YES not enough people do this. MB has a stupid spray thats bespoke for specifically that job, the 3M silicone spray works in a pinch. I would also check your drains make sure you're good.

I bought my E550 at around this mileage, you just gotta do your filters, smell for oil/coolant leaks. They're particular about battery health, so every 3 years about, change the battery on your remote if you need stuff to do, always good.

 

You can get the Shell ATF 134 FE from a shell distributor. I need to get a case soon, haven't priced it lately, it's 12 quarts in a case. People have also said you can go to a Shell station and have that station order a case for you if there isn't a distributor near you.

Oh yeah Maxlife is a hoot. I think it says it works in both 236.14 and 236.15 but if you look at the spec sheets for the particular fluid, they both say don't mix the two fluids. Yet we have a fluid that's suitable for both specs according to the maker of the fluid even though both specs say not to mix it. Needless to say Maxlife isn't on the approved list for either spec although Vavoline does have fluids on MB's approved list although you never see them in the stores, you just see Maxlife which is one size fits most. Still it seems to work ok, people do use it.

https://www.shell.us/business-custom...r-locator.html

 

I'm NOT gonna recommend anybody to use it so I don't look stupid here since we're all about specs and homework and TSB's here, but I may or may not have a few S550's running on it with huge success. It's a wonderful formula which is very cost effective, and it holds up really well based on what I see in the drains. It IS Valvoline after all so I have every reason to believe them when they say a fluid works for a given application. Every part of everything I know about 236.15 says do not mix it with anything, but so far I have mixed it with Maxlife (do not do this unless you are me), I've mixed it with the gold Ravenol 236.17 stuff too with great success (it lasts longer, don't ask me why), per my good friends at FCPEuro's recommendation. Again don't do this, just use the Febi/Bilstein, Pentosin, Shell, Ravenol, stuff that is approved by BEVO so you can sleep at night. I'm currently running Amsoil Signature FE ATF with great success so far but I don't have a ton of miles on it yet so I won't recommend it til I get to 40k or so which is when the Shell fill starts to fail in my experience.

DAMN the shell stuff is VERY reasonable! If I wasn't an AMS dealer or had same-day access to Febi through Worldpac I'd stock this FOR SURE over using the dealer stuff. It's $7/liter, shipping is $25 which is a little brutal.

 

Thanks guys! All good stuff to take into consideration. And I'll definitely be doing the ATF flush, that's at the top of my list.

 

Yeah, that's why you pick it up from a local distributor. I have one that's a few towns over, but I'm in the area once in a while so it's not really a special trip to go over there. It's funny when I call them, they say something like I've got 180 cases of that, how many do you want? Just one...